Wholly aromatic polyester resins have long been known. For instance, 4-hydroxybenzoic acid homopolymer and copolymers have been provided in the past and are commercially available. Such polymers commonly are crystalline in nature, relatively high melting or possess a decomposition temperature which is below the melting point, and when molten frequently exhibit an isotropic melt phase. Molding techniques such as compression molding or sintering may be utilized with such materials. Representative publications which discuss these wholly aromatic polyesters include: (a) Polyesters of Hydroxybenzoic Acids, by Russell Gilkey and John R. Caldwell, J. of Applied Polymer Sci., Vol. II, Pages 198 to 202 (1959), (b) Polyarylates (Polyesters From Aromatic Dicarboxylic Acids and Bisphenols), by G. Bier, Polymer, Vol. 15, Pages 527 to 535 (August 1974), (c) Aromatic Polyester Plastics, by S. G. Cottis, Modern Plastics, Pages 62 and 63 (July 1975), and (d) Poly(p-Oxybenzoyl Systems): Homopolymer for Coatings: Copolymers for Compression and Injection Molding, by Roger S. Storm and Steve G. Cottis, Coatings Plast. Preprint, Vol. 34, No. 1, Pages 194 to 197 (April 1974). See also, U.S. Pat. Nos. 3,039,994; 3,169,121; 3,321,437; 3,553,167; 3,637,595; 3,651,014; 3,662,052; 3,668,300; 3,723,388; 3,759,870; 3,767,621; 3,773,858; 3,787,370; 3,790,528; 3,829,406; 3,857,814; 3,884,876; 3,890,256; 3,974,250; and 3,975,487; and U.K. patent application No. 2,058,102A.
It has been disclosed that certain polyesters may be formed which exhibit melt anisotropy. See, for instance, (a) Polyester X7G-A Self Reinforced Thermoplastic, by W. J. Jackson, Jr., H. F. Kuhfuss, and T. F. Gray, Jr. 30th Anniversary Technical Conference, 1975 Reinforced Plastics Composites Institute, The Society of the Plastics Industry, Inc., Section 17-D, Pages 1-4, (b) Belgian Pat. Nos. 838,935 and 828,936, (c) Dutch Pat. No. 7505551, (d) West German Pat. Nos. 2520819, 2520820, 2722120, 2834535, 2834536 and 2834537, (e) Japanese Pat. Nos. 43-223; 2132-116; 3017-692; and 3021-293; (f) U.S. Pat. Nos. 3,991,013; 3,991,014; 4,057,597; 4,066,620; 4,067,852; 4,075,262; 4,083,829; 4,093,595; 4,118,372; 4,130,545; 4,130,702; 4,146,702; 4,153,779; 4,156,070; 4,159,365; 4,161,470; 4,169,933; 4,181,792; 4,183,895; 4,184,996; 4,188,476; 4,201,856; 4,219,461; 4,224,433; 4,226,970; 4,230,817; 4,232,143; 4,232,144; 4,238,598; 4,238;599; 4,238,600; 4,242,496; 4,245,082; 4,245,084; 4,247,514; 4,256,624; 4,265,802; 4,267,304; 4,269,965; 4,272,625; 4,279,803; 4,285,852; 4,287,332; 4,294,955; 4,299,756; 4,314,073; 4,318,841; and 4,318,842; and (g) U.K. application No. 2,002,404.
Representative disclosures of anisotropic melt forming polyesters or poly(ester-amides) which may include 2,6-dicarboxynaphthalene moiety and/or 2,6-dioxynaphthalene moiety are present in U.S. Pat. Nos. 4,067,852; 4,083,829; 4,093,595; 4,118,372; 4,130,545; 4,156,070; 4,169,933; 4,181,792; 4,184,966; 4,188,476; 4,201,856; 4,242,496; 4,247,514; 4,294,955, and commonly assigned U.S. Ser. Nos. 270,439, filed June 4, 1981 (now U.S. Pat. No. 4,339,375), and 270,440, filed June 4, 1981 (now U.S. Pat. No. 4,355,134). Also, U.K. patent application No. 2,058,102A discloses the use in ovenware of a broadly defined class of polyesters which may include dicarboxynaphthalene moiety and/or dioxynaphthalene moiety of unspecified symmetry.
It is an object of the present invention to provide a novel polyester which is capable of forming an optically anisotropic melt phase, and which may readily be melt processed to form quality fibers, films, three-dimensional molded articles, etc.
It is an object of the present invention to provide a novel polyester capable of forming an optically anisotropic melt phase which is derived from a specific combination of aromatic diols and aromatic diacids which are each free of ring substitution.
It is an object of the present invention to provide a novel polyester capable of forming an optically anisotropic melt phase which possesses a highly linear polymer chain which contributes to the stiffness characteristics of shaped articles comprising the same.
It is an object of the present invention to provide a novel polyester capable of forming an optically anisotropic melt phase which is derived from specified moieties in the absence of moieties derived from hydroxy acids which would impart different bond angles to the polymer chain.
These and other objects, as well as the scope, nature, and utilization of the claimed invention will be apparent to those skilled in the art from the following detailed description and appended claims.